1. The field of art to which the invention pertains includes the art of fluid handling with atmospheric venting.
2. Common construction at gasoline service station sites includes an aboveground atmospheric vent for the underground storage tank that enables release of pressurized vapors during fillup or the like, while allowing inbreathing of the tank as tank pressure is reduced. With the advent of vapor recovery systems designed to meet requirements of governing bodies, e.g. California Air Resources Board and Environmental Protection Agency, regulations require a restrictive device in the vent lines for reducing the escape of hydrocarbon vapors therefrom to atmosphere. In order to generally protect the discharge of the restrictive devices from adverse effects of weather, a form of weatherhood or breather vent have customarily been provided. The requirements for such vents are governed by NFPA Code 30-2240 "Vent pipes shall discharge only upward in order to dispense vapors".
Typically, available hoods or vents define a sinuous flow path of sorts from the vent pipe to an outlet reasonably protected by baffles or the like against in-flow of rain or snow. While functioning well under normal weather conditions, including conventional rain and snowfall, it has been found that such prior art hoods and vents fail to vent upwardly and/or tend to become blocked in the event of prolonged freezing rain or snow buildup that produce ice formations over their outlets. This, of course, impairs the venting function of the system, yet despite recognition of the problem a ready solution has not heretofore been known.